Wither roses drop even if domobloot is set to false

When the game rule mob loot is turned off using the command "/gamerule domobloot", the command doesn't get fully implemented. When the wither kills any mob, they still do drop wither roses.

Steps to Reproduce:

1. Create a new world
2. Set the domobloot gamerule to false
3. Summon a wither
4. Spawn a mob nearby
5. Wait for the wither to kill the mob

Observed Results:
The mob drops a wither rose when killed.

Expected Results:
Wither roses should not drop.